The present invention relates to an improved liquid fuel burner, and more particularly relates to an improvement for complete fuel burning in a burner in which liquid fuel such as kerosene is subjected to two-staged combustion.
As is well known, a liquid fuel burner includes an air supply duct, a fuel supply line, a fuel carburetor, a scatter ring coupled to the fuel carburetor for pulverization of liquid fuel and a perforated combustion cylinder defining internally a combustion chamber and externally a gas chamber.
In operation, supplied liquid fuel flows, in a thin layer form, along the inner wall of the fuel carburetor towards the scatter ring which by its high speed rotation pulverizes the liquid fuel for production of atomized fuel. Mixture of the atomized fuel with fresh air supplied through the air supply duct is ignited in the combustion chamber for primary combustion. This primary combustion heats the fuel carburetor for evaporation of the liquid fuel therein and fuel-air mixture is subjected to secondary combustion in the combustion chamber after passage through the gas chamber surrounding the perforated combustion cylinder.
Burning condition of the liquid fuel is subtly swayed by various factors, and delicate adjustment of these factors is necessary for complete burning of the fuel in the burner. First, it is required for the liquid fuel to form a thin and uniform layer on the inner wall of the fuel curburetor in order to enable sufficient pulverization for the primary combustion and rich and swift evaporation for the secondary combustion. Secondly, the scatter ring is required to have a function to produce highly atomized fuel and distribute the atomized fuel over broad area on the inner wall of the combustion cylinder.
In order to suffice these requirements, it was proposed to provide a scatter ring with an indented peripheral edge by, for example, forming radial cutouts in the edge. This proposed construction, however, cannot well avoid local shortage of air in the combustion chamber due to its rather poor air drag, thereby causing generation of a great deal of soot on the outer wall of the fuel carburetor.
Thirdly fuel drop in the burner forms a serious bar to complete burning of the fuel. The first fuel drop is caused by concentration of the liquid fuel on the outer wall of the air supply duct which is constantly cooled by supply of fresh air. Ths second fuel drop takes place at the open front end of the combustion cylinder. Such fuel drop is quite unavoidable in practice.